Very difficult. Way too difficult for me. I'm still not even sure what the walls do. I had a tree spawn on a wall. Is that a bug or do I just not know what the wall does. Amazing idea overall, but tune down the difficulty. I found myself running out of money over and over again. It would be better if you could save money. It allows you to debate if you should save for next time and allows you to get out of sticky situations if you had the foresight.